Section 86.1912 - How do I determine whether an engine meets the vehicle-pass criteria?In general, the average emissions for each regulated pollutant must remain at or below the NTE threshold in paragraph (a) of this section for at least 90 percent of the valid NTE sampling events, as defined in paragraph (b) of this section. For 2007 through 2009 model year engines, the average emissions from every NTE sampling event must also remain below the NTE thresholds in paragraph (g)(2) of this section. Perform the following steps to determine whether an engine meets the vehicle-pass criteria:
(a) Determine the NTE threshold for each pollutant subject to an NTE standard by adding all three of the following terms and rounding the result to the same number of decimal places as the applicable NTE standard:(1) The applicable NTE standard.(2) The in-use compliance testing margin specified in § 86.007-11(h) , if any.(3) An accuracy margin for portable in-use equipment when testing is performed under the special provisions of § 86.1930 , depending on the pollutant, as follows: (v) NOX + NMHC: 0.67 g/hp·hr.(4) Accuracy margins for portable in-use equipment when testing is not performed under the special provisions of § 86.1930 for 2007 through 2009 model year engine families that are selected for testing in any calendar year as follows:(i) NMHC using the emission calculation method specified in 40 CFR 1065.650(a)(1) : 0.02 g/hp·hr.(ii) NMHC using the emission calculation method specified in 40 CFR 1065.650(a)(3) : 0.01 g/hp·hr.(iii) NMHC using an alternative emission calculation method we approve under 40 CFR 1065.915(d)(5)(iv) : 0.01 g/hp·hr.(iv) CO using the emission calculation method specified in 40 CFR 1065.650(a)(1) : 0.5 g/hp·hr.(v) CO using the emission calculation method specified in 40 CFR 1065.650(a)(3) : 0.25 g/hp·hr.(vi) CO using an alternative emission calculation method we approve under 40 CFR 1065.915(d)(5)(iv) : 0.25 g/hp·hr.(vii) NOX using the emission calculation method specified in 40 CFR 1065.650(a)(1) : 0.45 g/hp·hr.(viii) NOX using the emission calculation method specified in 40 CFR 1065.650(a)(3) : 0.15 g/hp·hr.(ix) NOX using an alternative emission calculation method we approve under 40 CFR 1065.915(d)(5)(iv) : 0.15 g/hp·hr.(x) NOX + NMHC using the emission calculation method specified in 40 CFR 1065.650(a)(1) : 0.47 g/hp·hr.(xi) NOX + NMHC using the emission calculation method specified in 40 CFR 1065.650(a)(3) : 0.16 g/hp·hr.(xii) NOX + NMHC using an alternative emission calculation method we approve under 40 CFR 1065.915(d)(5)(iv) : 0.16 g/hp·hr.(xiii) PM: 0.006 g/hp·hr.(5) Accuracy margins for portable in-use equipment when testing is not performed under the special provisions of § 86.1930 for 2010 or later model year engines families that are selected for testing in any calendar year as follows: (i) NMHC using any emission calculation method specified in 40 CFR 1065.650(a) or an alternative emission calculation method we approve under 40 CFR 1065.915(d)(5)(iv) : 0.01 g/hp·hr.(ii) CO using any emission calculation method specified in 40 CFR 1065.650(a) or an alternative emission calculation method we approve under 40 CFR 1065.915(d)(5)(iv) : 0.25 g/hp·hr.(iii) NOX using any emission calculation method specified in 40 CFR 1065.650(a) or an alternative emission calculation method we approve under 40 CFR 1065.915(d)(5)(iv) : 0.15 g/hp·hr.(b) For the purposes of this subpart, a valid NTE sampling event consists of at least 30 seconds of continuous operation in the NTE control area. An NTE event begins when the engine starts to operate in the NTE control area and continues as long as engine operation remains in this area (see § 86.1370 ). When determining a valid NTE sampling event, exclude all engine operation in approved NTE limited testing regions under § 86.1370-2007(b)(6) and any approved NTE deficiencies under § 86.007-11(a)(4)(iv) . Engine operation in the NTE control area of less than 30 contiguous seconds does not count as a valid NTE sampling event; operating periods of less than 30 seconds in the NTE control area, but outside of any allowed deficiency area or limited testing region, will not be added together to make a 30 second or longer event. Exclude any portion of a sampling event that would otherwise exceed the 5.0 percent limit for the time-weighted carve-out defined in § 86.1370-2007(b)(7) . For EGR-equipped engines, exclude any operation that occurs during the cold-temperature operation defined by the equations in § 86.1370-2007(f)(1) .(c) Calculate the average emission level for each pollutant over each valid NTE sampling event as specified in 40 CFR part 1065, subpart G, using each NTE event as an individual test interval. This should include valid NTE events from all days of testing.(d) If the engine has an open crankcase, account for these emissions by adding 0.00042 g/hp·hr to the PM emission result for every NTE event.(e) Calculate a time-weighted vehicle-pass ratio (Rpass) for each pollutant. To do this, first sum the time from each valid NTE sampling event whose average emission level is at or below the NTE threshold for that pollutant, then divide this value by the sum of the engine operating time from all valid NTE events for that pollutant. Round the resulting vehicle-pass ratio to two decimal places. (1) Calculate the time-weighted vehicle-pass ratio for each pollutant as follows: View Image
Where:
npass = the number of valid sampling events for which the average emission level is at or below the NTE threshold.
ntotal = the total number of valid NTE sampling events.
(2) For both the numerator and the denominator of the vehicle-pass ratio, use the smallest of the following values for determining the duration, t, of any NTE sampling event: (i) The measured time in the NTE zone that is valid for an NTE sampling event.(iii) 10 times the length of the shortest valid NTE sampling event for all testing with that engine.(f) The following example illustrates how to select the duration of NTE sampling events for calculations, as described in paragraph (f) of this section: | NTE sample | Duration of
NTE sample
(seconds) | Duration limit applied? | Duration
used in
calculations
(seconds) |
| 1 | 45 | No | 45 |
| 2 | 168 | No | 168 |
| 3 | 605 | Yes. Use 10 times shortest valid NTE | 450 |
| 4 | 490 | Yes. Use 10 times shortest valid NTE | 450 |
| 5 | 65 | No | 65 |
(g) Engines meet the vehicle-pass criteria under this section if they meet both of the following criteria: (1) The vehicle-pass ratio calculated according to paragraph (e) of this section must be at least 0.90 for each pollutant.(2) For model year 2007 through 2009 engines, emission levels from every valid NTE sampling event must be less than 2.0 times the NTE thresholds calculated according to paragraph (a) of this section for all pollutants, except that engines certified to a NOX FEL at or below 0.50 g/hp·hr may meet the vehicle-pass criteria for NOX if measured NOX emissions from every valid NTE sample are less than either 2.0 times the NTE threshold for NOX or 2.0 g/hp·hr, whichever is greater. 81 FR 73998 , Oct. 25, 2016